1. Field of the Invention
The present invention relates generally to a system for controlling dust and other particulates, and more particularly to a system for removing dust and other particulate matter from an air stream.
2. Background
Dust generation by agricultural and construction machinery is a known problem, particularly in arid areas. To name just a few problems caused by the dust generation, dust particles result in air pollution, water pollution, soil loss, human and animal health problems, and potentially hazardous reductions in visibility. In addition, the dust can adversely impact the health of various plants. In an effort to reduce dust production, some air pollution control districts impose various operating limitations on farm machinery or otherwise impose different dust control measures.
Dust generation from nut and fruit harvesting equipment can be particularly problematic. These devices typically utilize high volume fans to separate nuts and/or fruit from the debris which may be picked up by the harvesting equipment, including leaves, branches, dirt clods, soil, etc. (collectively, “foreign material”). However, a large portion of the foreign material is typically blown out through the fan discharge, resulting in the dispersion of a large volume of dust into the atmosphere. An example of such a harvester is disclosed in U.S. Pat. No. 4,364,222, which is incorporated herein by this reference. In these devices, a mixture of fruit or nuts (generally referred to as “crops”) and foreign material is picked up and deposited on conveyors enclosed by a housing connected to a fan inducing a vigorous flow of air through the conveyors. Various baffles, walls and guide plates direct the air so as to enhance the separation of the desirable crops from the foreign material. However, a substantial volume of foreign material is typically discharged into the atmosphere with a minimum amount of processing, thus creating a large discharge of dust.
In addition to the agricultural settings described above, dust and other particulates may be present in an air stream under a variety of circumstances. Regardless of the cause of the introduction of such particulates into the air, the hazards and disadvantages above remain present. A number of devices have been developed to remove dust and other fine particles from an air stream. Electrostatic filters, for example, use an electrical field and rely on the action of electrostatic forces to remove particles from an air stream. Such filtration devices can suffer from a non-homogeneous flow of air in proximity to the electrostatic plates and may also fail to function as well when humidity is high. Mechanical filters are also known, and while these are often effective they can result in significant head loss and are also prone to becoming clogged by particles being filtered from the air stream.
International Publication No. WO 2006/092702 A2, entitled “Cleaner for Air Polluted by Fine Dusts and Relative Purifying Process,” by Cirillo et al., described a system for removing fine dust particles from an air stream. In that device, a stream of air impacts a rotating brush and the fine particles in the air adhere to the brush. The rotational speed of the brush is such that the fine particles migrate to the tips of the brush through centrifugal force and are then cast off of the brush into the housing of the device. Although Cirillo et al. provide a perforated wall through which the particles preferably pass, the rapid rotation of the brushes of Cirillo et al. necessarily result in a more or less uniform distribution of cast off particles within the device, rather than deposited the particles in a more precise location. Further, enough energy must be provided to the device of Cirillo et al. to maintain sufficient rotational speeds of the brush to allow the centrifugal forces to act as suggested by that disclosure.
What is needed, then, is a device and system that can be used in a variety of circumstances, and under a variety of conditions, to remove dust and other particulate matter from the air.